Can you please help me with my homework i have a picture

In triangle abc segment de is parallel to the side ac . (the endpoints of segment de lie on the sides ab and bc respectively). find de, if ac=20cm, ab=17cm, and bd=11.9cm;

Scrub a dub toothbrushes are $4.00 each. there is a 10% discount, but there is also a 6% sales tax after the discount is applied. what is the new price after tax? round to the nearest penny

If f(x) = 4x – 3 and g(x) = 8x + 2, find each function value a.f[g(3)] b.g[f(5)] c.g{f[g(-4)]}